The subject matter disclosed herein relates to power generation systems. Specifically, the embodiments described herein relate to controlling a turbine system in low ambient temperatures.
In a power generation system, such as a gas turbine system, a compressor may be used to compress a fluid (e.g., air) prior to mixing the fluid with fuel for combustion. In low ambient temperatures, the power generation system may be configured to observe and maintain the operating limit of the compressor, particularly when the power generation system uses a low British Thermal Unit (BTU) fuel. Low BTU fuels include fuels that may have large concentrations of inert gases, synthetic gases, waste gases, and biomass gases.
To maintain the operating limits of the compressor in low ambient temperature conditions, the power generation system may be configured to intentionally under-fire. That is, the fuel flow is often reduced to account for reduced compression due to the design limits of the compressor in low ambient temperatures. Reducing the fuel flow may in turn lead to lower firing temperatures for the power generation system. However, intentionally under-firing the power generation system may also result in output loss, in terms of the power generated by the power generation system as well as a loss of exhaust energy which may be captured and used by other components, such as a heat steam recovery generator (HSRG). It would be beneficial to operate power generation systems in low ambient temperatures, particularly when utilizing low BTU fuels, such that the system maintains the compressor limits while minimizing intentional under-fire.